Improve project avatars for dashboard

Fixes #1955

See merge request !1457

Make omnibus the default in repo import docs

I hope this reads nicer for people using omnibus packages.

See merge request !1420

Search group documentation

See merge request !1455

Fix RepositoryCache backend attr_reader

Make the structure of spec/models match app/models

Bump GitLab for Docker to version 7.7.2

See merge request !324

Update doc needs libkrb5 dev

People who use the update guide should also install libkrb5-dev.

See merge request !1454

Add icon helper method

Use pry-rails gem instead of pry

Minor spec output cleanup

Improve calendar widget

See merge request !1453

Expose Link header in CORS Api calls

* cache user contributions for day
* ignore forks in calendar contribtuions

Refactor Repository to use new RepositoryCache class

Improvements to LDAP::User model

* method #changed? also tracks changes of identites (fixes issue with email mapping)
* find ldap identity before initialize one

Fixes #1946

See merge request !1452

* method #changed? also tracks changes of identites (fixes issue with email mapping)
* find ldap identity before initialize one

This outdated gem was the cause of those annoying MiniTest errors.

Also updates one use of `ensure_inclusion_of` which was deprecated in
favor of `validate_inclusion_of`.

This caused those random "true" outputs in the rspec output.

pry-rails has pry as a dependency and this lets us have all that pry
when we run `rails console` ❤

Abstracts away the lower-level implementation details from the
Repository model.